Chemistry TCB Exam Flashcards

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chemistry =
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study of substances and the changes they undergo
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Describe the Atlantic/Pacific rule.
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decimal Absent: start on the Atlantic side of the number, count the first non-zero number and all that follow

decimal Present: start on Pacific side of the number, count the first non-zero number and count all that follow

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How many sig figs do I use when measuring things in lab situations?  (ex. graduated cylinder or ruler)
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go to the nearest line given, then estimate one decimal past that (if a graduated cylinder shows lines every 1mL, your answer should be to the nearest 1/10mL  ex. 10.5mL)
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accuracy
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how close a measurement is to the real answer
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precision
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how close a measurement is to other measurements
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How many sig figs in:

7.2340

0.03460

1,340.01

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5

4

6

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How do we measure density?
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mass/volume
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Put the following in scientific notation:

5,245,252

0.00346

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5.25x10^6

3.46x10^-3

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If I shoot my bow, and I consistently hit low and to the left, are my shots precise or accurate or both?
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precise (the shots are consistent, but not accurate, that is, they're not close to the bullseye)
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Convert the following:

1,288 inches = ____? meters

2.54cm / inch

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3,271.52cm

or

3,270cm (3 sig figs)

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independent variable
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the thing I change/control
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dependent variable(s)
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the thing(s) you measure
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law of conservation of energy
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energy is neither created or destroyed
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law of conservation of mass
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mass is neither created or destroyed
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law of conservation of matter
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matter is neither created or destroyed
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Which can NOT be broken down any further?

sodium, disulfate, diatomic oxygen, hydroxide

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sodium, because its an element.; The rest are either molecules or compounds
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Is a phase change a chemical change or a physical change?
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Physical change because its only changing forms, not creating something new
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chemical change
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when a chemical reaction takes place and new products are formed
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Which state of matter is typically the LEAST dense?
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Gas
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What is an alpha particle?
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a helium nucleus (2 protons, 2 neutrons)
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How do you balance nuclear equations?
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balance the top number (mass number) and balance the bottom number (atomic number)
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If the result of a nuclear equation is a particle with a mass number of 4 and atomic number of 2, what type of nuclear reaction happened?
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alpha decay, because an alpha particle has an atomic # of 2 and mass # of 4.
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If the result of a nuclear equation is a particle with a mass number of 0 and atomic number of -1, what type of nuclear reaction happened?
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beta decay, because the result of beta decay is the decay of a neutron into a proton and the release of an electron
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Match the scientist:

Bohr;;;;;;;;;;;;;;;;;; gold foil experiment

JJ Thomson;;;;;;; planet model of atom

Rutherford;;;;;;;; ; ; ; ; ; ;; plum pudding

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Bohr:; planetary model

Thomson:; plum pudding

Rutherford:; gold foil

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What did the gold foil experiment done by Rutherford prove?
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atoms have very tiny, but very dense nuclei
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If I started with 48g of Carbon-12, and 1yr later I have 38g, what term describes what has happened?
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radioactive decay
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If the half-life of carbon-12 is 5.73yrs, and I started with 100g, how much is left after 11.46yrs?
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25 grams

because 11.46yrs is 2 half-lives

100g-->50g-->25g

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How many half-lives does it take to have 1/16 of the original sample left?
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4 half-lives

1-->1/2-->1/4-->1/8-->1/16

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If the mass number of element X is 48, and it has 22 protons, how many neutrons does it have?
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26 neutrons

48 - 22 = 26

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If the atomic number of element X is 43 and it contains 41 electrons, what is the ion charge?
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+2

 

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What does the neutron do for an atom?

 

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Three important things:

1.  it supplies the force that holds the nucleus together

2.  it makes the atom more stable

3.  it is the "glue" of the nucleus

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What is the atomic mass of element X:

isotope 1: 18.32amu, abundance 21.30%

isotope 2: 19.27amu, abundance 70.20%

isotope 3: 20.11amu, abundance 8.50%

answer

19.14amu

18.32 x .2130 = 3.90

19.27 x .7020 = 13.53

20.11 x .0850 = 1.71

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electrons have several energy levels, which contain _____, which contain _______ that each hold a pair of electrons.
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sublevels

orbitals

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s, p, d and f describe what?
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electron sublevels (and areas on the periodic table that contain those sublevels)
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What is the shape of the s-sublevel?
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sphere
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What is the shape of the p-sublevel?
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dumb bell shape
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How many valence electrons do the following have?

Na, C, Ne

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Na = 1

C = 6

Ne = 8

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What element has the same electron configuration as Al+3?
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Neon

because aluminum lost 3 electrons, giving it the same configuration as the element with 3 less electrons

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If we vaporize an element in a flame, what type of light is given off?
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only specific wavelengths of light, which are based on the energy given off by the electrons as they fall back to their "ground state"
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What color of light has the highest energy? lowest?
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highest: violet

lowest: red

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What is the electron configuration for Fe (iron)?
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1s2, 2s2, 2p6, 3s2, 3p6, 4s2, 3d8
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Why are valence electrons important?
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they are the electrons involved in reactions and bonding
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What halogen has the highest ionization energy? Why?
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Fluorine because its outermost electron is closest to the nucleus
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ionization energy
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energy needed to "pluck" an electron from an atom;  increases as you go right and up on the periodic table
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Ionization energy is similar to what other trend on the periodic table?
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electron affinity
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atomic radius
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measure of the size of an atom; it increases down a group, but decreases across a period
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Why does atomic radius decrease across a period?
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because as electrons and protons are added, the attraction between the nucleus and electrons increases, making the atom more "condensed"
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When an atom gains electrons, it
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gets larger

becomes an ion

has a negative charge

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Metals typically form ___ ions and are found on the ___ of the periodic table.  Non-metals typically form ___ ions and are found on the ___ of the periodic table.
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positive, left

negative, right

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What is the difference between ionization energy and electron affinity?
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ionization energy= energy required to "pluck" an electron from the atom

electron affinity= energy given off when an electron is gained

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Which "block" contains the alkali metals and alkaline earth metals?
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s-block
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Which "block" contains the non-metals?
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p-block
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Which "block" contains the transition metals?
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d-block
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What makes transition metals unique?
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They are:

good conductors of heat/electricity

shiny, malleable, ductile

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What makes alkali metals and alkaline earth metals unique?
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they are highly reactive, soft metals
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What makes the halogens unique?
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they are highly reactive non-metals
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Air is a mixture of gases including oxygen, nitrogen, helium, hydrogen and traces of other gases.  Which gas makes up most (70+%) of earth's air?
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nitrogen
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Which "block" on the periodic table is the only one that contains both metals and non-metals?
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p-block
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What is the formula for the following:

sulfate

sulfide

ammonia

ammonium

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SO4-2

S-2

NH3

NH4+1

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When atoms lose or gain electrons, they are trying to form stable electron configurations similar to which family?
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noble gases
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Name the compound:

NaNO3

SBr3

CaF2

KCl * 5H2O

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sodium nitrate

sulfur tribromide

calcium fluoride

potassium chloride pentahydrate

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When is the prefix "mono" used in naming compounds?
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only on the second word of a covalent compound, never on the first.
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What does the Roman numeral next to a transition metal tell you?

ex. copper (II) sulfate

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it tells you the ion charge (positive) on the transition metal
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What does an acid have in its formula?

What does a base have in its formula?

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H+ ion

OH- ion

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Which is the stronger covalent bond, a single bond or double bond or triple bond?
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triple is strongest, then double, then single
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Which covalent bonds are the longest, single, double or triple bonds?
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single bonds are longest, then double, then triple
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How many single covalent bonds can one carbon atom have?
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4
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alkane
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single chain hydrocarbon with the formula

CnH*2n +2

ex. C8H18

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What does "Max eats peanut butter" refer to?
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naming alkanes and alcohols

Max = methane/methanol

eats = ethane/ethanol

peanut = propane/propanol

butter = butane/butanol

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allotrope
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a pure substance with different structural forms
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What are the three most common allotropes of carbon?
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graphite

diamond

buckminster fullerine (buckyball)

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alcohol
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a hydrocarbon in which a hydroxide (OH) has replaced CH3 on one side of an alkane

ex. ethane = CH3CH2CH3

ethanol = CH3CH2OH

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What are alcohols most used for?
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they are burned for fuel
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alloy
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a mixture containing metals produced by melting them together
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Which of the following is NOT an alloy?

steel

bronze

silver

brass

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silver, it is an element
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molarity
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moles per liter

mol/L

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molality
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moles per kilogram

mol/kg

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What formula do we use to calculate Molarity?
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Molarity = # mols / molar mass
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In words, what is molarity?
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concentration of a substance in a liquid (usually water)
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How do we figure out the number of mols of a substance?
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# mols = grams of substance / molar mass
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How do we figure out molar mass?
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1. Look up each element's mass

2. Multiply by the # of atoms of that element

3.  Add all the numbers together

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What is Avogadro's Number?
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6.02 X 10^23

or 1 mole

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How do we calculate the number of particles of a substance?
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# particles = (# mols ) X (6.02 X 10^23)
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What type of reaction is shown below?

 

2HgO --->  2Hg + O2

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decomposition reaction
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What type of reaction is shown below?

 

2Mg + O2 --->  2MgO

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combination reaction OR

synthesis reaction

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What type of reaction is shown below:

 

2K + 2H2O --->  2KOH + H2

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single replacement reaction
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What type of reaction is shown below:

 

Br2 + 2NaI --->  2NaBr + I2

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single replacement reaction
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What must be true for a metal to replace another metal (or hydrogen) in a single replacement reaction?
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it must be more reactive (from the activity series chart) than the one it replaces
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What type of reaction is shown below:

 

Na2S + Cd(NO3)2 --->  CdS + 2NaNO3

answer
double replacement reaction
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Balance this reaction:

 

NaCN + H2SO4 --->  HCN + Na2SO4

answer
2NaCN + H2SO4 --->  2HCN + Na2SO4
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Balance this equation, give the type of reaction and name the compounds:

 

Ca(OH)2 + HCl --->  CaCl2 + H2O

answer

Ca(OH)2 + 2HCl --->  CaCl2 + 2H2O

double replacement reaction

calcium hydroxide + hydrogen chloride (hydrochloric acid)  ---> calcium chloride + dihydrogen monoxide (water)

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What type of reaction is shown below,  and name the compounds:

 

2C8H18 + 25O2 --->  16CO2 + 18H2O

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combustion (burning) reaction

 

octane (gasoline) + diatomic oxygen (oxygen gas) --->  carbon dioxide + dihydrogen monoxide (water)

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How many total electrons are involved in a double covalent bond?
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4
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polarity
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describes if a molecule has a positive side and a negative side; like a magnet
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How do we determine whether a molecule is polar or non-polar?
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check the electronegativity chart: 

a difference greater than 0.4 means polar...if the molecule is diatomic, it must be non-polar

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electronegativity
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a number given to elements to describe "how negative" or "how positive" they are
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Determine if the following is polar or non-polar:

Na2S

O2

TeCl2

Electronegativities: Na=0.9  S=2.5  O=3.5  Te=2.1  Cl=3.0

answer

Na2S  --->  polar (EN:  2.5-0.9=1.6)

O2 ---->  non-polar (diatomic)

TeCl2 ----> polar (EN: 3.0-2.1=0.9)

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